Fluoropolymer bonding composition and method

ABSTRACT

A multi-layer structure includes a fluoropolymer bonded to a substrate. The structure is prepared by exposing a bonding composition to actinic radiation, such as ultraviolet radiation, to form the bond. The bonding composition includes a light-absorbing compound and an electron donor. The bonding composition includes non-adhesive materials.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of U.S. Ser. No. 09/862,022,filed May 21, 2001, now allowed, the disclosure of which is hereinincorporated by reference.

TECHNICAL FIELD

[0002] This invention relates to methods and compositions for bonding afluoropolymer to a substrate.

BACKGROUND

[0003] Fluorine-containing polymers (also known as “fluoropolymers”) area commercially useful class of materials. Fluoropolymers include, forexample, crosslinked fluoroelastomers and semi-crystalline or glassyfluoropolymers. Fluoropolymers are generally of high thermal stabilityand are particularly useful at high temperatures. They may also exhibitextreme toughness and flexibility at very low temperatures. Many ofthese fluoropolymers are almost totally insoluble in a wide variety ofsolvents and are generally chemically resistant. Some have extremely lowdielectric loss and high dielectric strength, and may have uniquenon-adhesive and low friction properties. Fluoroelastomers, particularlythe copolymers of vinylidene fluoride with other ethylenicallyunsaturated halogenated monomers such as hexafluoropropylene, haveparticular utility in high temperature applications such as seals,gaskets, and linings.

[0004] Multi-layer constructions containing a fluoropolymer enjoy wideindustrial application. Such constructions find utility, for example, infuel line hoses and related containers and hoses or gaskets in thechemical processing field. Adhesion between the layers of amulti-layered article may need to meet various performance standardsdepending on the use of the finished article. However, it is oftendifficult to establish high bond strengths when one of the layers is afluoropolymer, in part, because of the non-adhesive qualities offluoropolymers. Various methods have been proposed to address thisproblem. One approach is to use an adhesive layer or tie layer betweenthe fluoropolymer layer and the second polymer layer. Surface treatmentsfor the fluoropolymer layer, including the use of powerful reducingagents (e,g., sodium naphthalide) and corona discharge, have also beenemployed to enhance adhesion. In the case of fluoropolymers containinginterpolymerized units derived from vinylidene fluoride, exposure of thefluoropolymer to a dehydrofluorinating agent such as a base has beenused, as well as polyamine reagents applied to the fluoropolymer surfaceor incorporated within the fluoropolymer itself.

SUMMARY

[0005] A multi-layer structure includes a fluoropolymer bonded to asubstrate. The structure is prepared by exposing a bonding compositionto actinic radiation, such as ultraviolet radiation, with optionalheating, pressure, or combination thereof, to form the bond. The bondingcomposition includes a light-absorbing compound and an electron donor.The bonding composition may be free of adhesive materials.

[0006] In one aspect, a method of bonding a fluoropolymer to a substrateincludes providing a bonding composition between a fluoropolymer and asubstrate, and exposing the bonding composition to actinic radiation.

[0007] In another aspect, a method of bonding a fluoropolymer to asubstrate includes providing a first substrate including a bondingcomposition, contacting the treated surface of the first substrate witha surface of a second substrate, and exposing the bonding composition toactinic radiation. The method may include applying heat, pressure, or acombination thereof, to form the bond. Each of the first substrate andthe second substrate, independently, includes a matrix material. Thematrix material can be a metal, a glass, an organic-inorganic composite,a fluoropolymer, and a non-fluorinated polymer with the proviso that atleast one of the first substrate and the second substrate is afluoropolymer.

[0008] The bonding composition may be provided between the fluoropolymerand the substrate in different ways. For example, a surface of thefluoropolymer may be treated with the bonding composition and thetreated surface of the fluoropolymer may be contacted with a surface ofthe substrate, or a surface of the substrate may be treated with thebonding composition and the treated surface of the substrate may becontacted with a surface of the fluoropolymer. In certain embodiments, amixture of the fluoropolymer and the bonding composition may be extrudedand a surface of the extruded mixture may be contacted with a surface ofthe substrate. In other embodiments, the substrate or the fluoropolymermay be cast from solution or polymerized from a monomer. The bondingcomposition may be exposed to actinic radiation before contacting.

[0009] In another aspect, a composite article includes a fluoropolymerhaving a surface, a substrate having a surface, and a bondingcomposition interposed between the surface of the fluoropolymer and thesurface of the substrate.

[0010] In yet another aspect, a treated fluoropolymer substrate suitablefor bonding to a polymeric substrate includes a surface exposed to acombination of a light-absorbing compound and an electron donor andactinic radiation.

[0011] In still another aspect, a laminated article including afluoropolymer is bonded to a substrate by a bonding compositionincluding a light-absorbing compound and an electron donor exposed toactinic radiation.

[0012] In another aspect, a composition includes a fluoroalkylamine,such as a 2,2,2-trifluoroethylamine.

[0013] The bonding composition includes a light-absorbing compound andan electron donor. The light-absorbing compound may be an ammoniumcompound, a phosphonium compound, a sulfonium compound, a sulfoxoniumcompound, an iodonium compound, an arsonium compound, or combinationsthereof. The ammonium compound or phosphonium compound may include abenzyl moiety. The electron donor may be an amine, a phosphine, athioether, or combinations thereof. The amine may be a primary amine, anamino-substituted organosilane, or combinations thereof. The amine maybe a mono-, di- or tri-alkylamine. The alkylamine can be afluoroalkylamine. The amino-substituted organosilane may have ahydrolyzable substituent. The bonding composition may include avinylsilane. The bonding composition may be exposed to actinic radiationthrough the fluoropolymer or the substrate.

[0014] The fluoropolymer may be a perfluorinated polymer or a partiallyfluorinated polymer. The substrate may include an inorganic substrate,such as a metal and a glass, or an organic substrate, such as anon-fluorinated polymer or fluoropolymer, or an organic-inorganiccomposite.

[0015] Bonded multi-layer materials may have combined physical andchemical properties possessed by both fluoropolymers and non-fluorinatedpolymers, resulting in less expensive, well-performing articles. Forexample, the fluoropolymer component may be used in automotive hose andcontainer constructions, anti-soiling films, low energy surface PSAtapes and coatings for aircraft. The bonding process is a mildphotochemical lamination that may promote adhesion between afluoropolymer and a substrate. The bonding composition may be used toform a composite article having a fluoropolymer cladding on a conductiveand lustrous metal to protect it from corrosion, a fluoropolymercladding on glass fibers to enhance their physical strength and chemicalresistance for telecommunication, or a fluoropolymer layer bonded to ahydrocarbon substrate in a multi-layer materials.

[0016] The details of one or more embodiments of the invention are setforth in the accompanying drawings and the description below. Otherfeatures, objects, and advantages of the invention will be apparent fromthe description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

[0017]FIG. 1 is a cross-sectional view of a multi-layer article.

DETAILED DESCRIPTION

[0018] A fluoropolymer layer may be bonded on one surface of a substrateto form, for example, a laminate. The laminate may contain two or morelayers. Referring to FIG. 1, the laminate 10 includes fluoropolymerlayer 20 and the substrate 30. Bonding composition 40 contacts theinterface between fluoropolymer layer 20 and substrate 30. Actinicradiation applied to the bonding composition promotes bonding betweenfluoropolymer layer 20 and substrate 30.

[0019] The bonding composition includes a light-absorbing compound andan electron donor. The bonding composition may include a solvent tofacilitate applying a coating of the composition to a surface of thefluoropolymers or the substrate, or both. The solvent may be removed,for example, by drying, prior to contacting the substrate andfluoropolymers surfaces. Any solvent, if used may be a fluorinatedsolvent, for example, a fluorinated solvent having at least onefluorinated moiety. Fluorinated solvents may be effective at promotingwetting of the bonding composition onto either substrate. Preferredfluorinated solvents include, for example, hexafluoroxylene,hexafluorobenzene, and the like.

[0020] Actinic radiation is electromagnetic radiation having awavelength capable of affecting bonding between the fluoropolymer andthe substrate in the presence of the bonding composition. The actinicradiation has an intensity at a wavelength capable of affecting bondingwithin a reasonable amount of time. The actinic radiation may have awavelength between 190 nm and 700 nm, preferably between 200 nm and 400nm, more preferably between 205 nm and 320 nm, even more preferablybetween 210 nm and 290 nm, and even more preferably between 240 nm and260 nm.

[0021] The actinic radiation has a wavelength that is absorbed by thelight-absorbing compound. The light-absorbing compound may have anabsorbing moiety capable of being excited by the actinic radiation, suchas, for example, a benzyl moiety or other aromatic moiety. Thelight-absorbing compound may be an ammonium compound, a phosphine, aphosphonium compound, an aromatic hydrocarbon compound, a thioethercompound, an ether compound, a phenolic compound, a sulfonium compound,a sulfoxonium compound, an iodonium compound, an arsonium compound, orcombinations thereof. Specific examples include triphenylphosphine,benzyltriphenylphosphonium chloride, benzyltributylammonium chloride, anarylammonium salt, tetraphenylarsonium chloride, diphenyl sulfide,biphenyl, 4,4′-dihydroxybiphenyl and triarylsulfonium chloride. Otherexamples of light-absorbing compounds are described, e.g., in Fukushi,U.S. Pat. No. 5,658,671, “Fluoroelastomer Coating Composition,” herebyincorporated by reference. The light-absorbing compound may have a molarabsorptivity of at least 100, preferably at least 500, more preferablyat least 1,500, even more preferably at least 5,000 at a wavelength whenexposed to actinic radiation. In some embodiments, the light-absorbingcompound may include individual components that do not significantlyabsorb actinic radiation in a purified state, but absorbs light when thecomponents are combined. For example, a component of the composite mayform a charge-transfer complex with the donor, fluoropolymer, substrateor other added ingredient, resulting in a compound that absorbs actinicradiation.

[0022] The electron donor is a compound capable of reducing the excitedstate of the light-absorbing compound. For example, the electron donormay be an amine, a phosphine, a thiol, a thioether, phenol, thiophenol,phenolate, thiophenolate or combinations thereof. The amine may be aprimary amine, such as an alkylamine, e.g., a monoalkylamine, adialkylamine, or a trialkylamine, such as a fluoroalkylamine. Theelectron donor may be polymerizable, for example, a polymerizable aminesuch as an aminoalkene or a vinylaniline. The amine may be anamino-substituted organosilane. The amino-substituted organosilane mayhave a hydrolyzable substituent; for example, it may be atrialkoxysilane. For example, the amino-substituted organosilane mayhave the formula

R¹R²N-L-SiXX′X″

[0023] where each of R¹ and R², independently, is H, C1-12 alkyl, C1-12alkenyl, C1-12 alkynyl, or aryl, and L is a divalent straight chainC1-12 alkylene, C3-8 cycloalkylene, 3-8 membered ringheterocycloalkylene, C1-12 alkenylene, C3-8 cycloalkenylene, 3-8membered ring heterocycloalkenylene, arylene, or heteroarylene. L isoptionally substituted with C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl, C1-4alkoxy, hydroxyl, halo, carboxyl, amino, nitro, cyano, C3-6 cycloalkyl,3-6 membered heterocycloalkyl, aryl, 5-6 membered ring heteroaryl, C1-4alkylcarbonyloxy, C1-4 alkyloxycarbonyl, C1-4 alkylcarbonyl, formyl,C1-4 alkylcarbonylamino, or C1-4 aminocarbonyl. L is further optionallyinterrupted by —O—, —S—, —N(Rc)—, —N(Rc)—C(O)—, —N(Rc)—C(O)—O—,—O—C(O)—N(Rc)—, —N(Rc)—C(O)—N(Rd)—, —O—C(O)—, —C(O)—O—, or —O—C(O)—O—.Each of Rc and Rd, independently, is hydrogen, alkyl, alkenyl, alkynyl,alkoxy, hydroxylalkyl, hydroxyl, or haloalkyl. Each of X, X′ and X″ is aC1-18 alkyl, halogen, C1-8 alkoxy, C1-8 alkylcarbonyloxy, or aminogroup. When the amino-substituted organosilane has a hydrolyzablesubstituent, at least one of X, X′, and X″ is not alkyl. Further, anytwo of X, X′ and X″ may be joined through a covalent bond. The aminogroup may be an alkylamino group.

[0024] The bonding composition may include other additives, for example,a vinylsilane, such as an alkoxyvinylsilane, polyhydroxy aromaticcompounds, or a thermosetting resin such as an epoxy resin, a urethaneresin, a urea resin, or an acrylate resin.

[0025] The fluoropolymer may be a perfluorinated polymer or a partiallyfluorinated polymer. For example, the fluoropolymer may be eithermelt-processible such as in the case of a terpolymer oftetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV™),a tetrafluoroethylene-hexafluoropropene copolymer (FEP), and othermelt-processible fluoroplastics, or may be non-melt processable such asin the case of polytetrafluoroethylene (PTFE), modified PTFE copolymers,such as a copolymer of TFE and low levels of fluorinated vinyl ethersand fluoroelastomers. Fluoroelastomers may be processed before they arecured by injection or compression molding or other methods normallyassociated with thermoplastics. Fluoroelastomers after curing orcrosslinking may not be not able to be further processed.Fluoroelastomers may also be coated out of solvent in their uncrosslinked form. Fluoropolymers may also be coated from an aqueousdispersion form. In preferred embodiments, the fluoropolymer may be FEP,a tetrafluoroethylene-perfluoropropyl vinyl ether copolymer (PFA),perfluoroelastomer, or mixtures thereof.

[0026] Preferably, the fluoropolymer is a material that is capable ofbeing extruded or solvent coated. Such fluoropolymers typically arefluoroplastics that have melting temperatures ranging from about 100 toabout 330° C., more preferably from about 150 to about 270° C. Preferredfluoroplastics include interpolymerized units derived from VDF andfluoroethylene and may further include interpolymerized units derivedfrom other fluorine-containing monomers, non-fluorine-containingmonomers, or a combination thereof.

[0027] Examples of suitable fluorine-containing monomers includetetrafluoroethylene (TFE), hexafluoropropylene (HFP),chlorotrifluoroethylene (CTFE), 3-chloropentafluoropropene,perfluorinated vinyl ethers (e.g., perfluoroalkoxy vinyl ethers such asCF₃OCF₂CF₂CF₂OCF═CF₂ and perfluoroalkyl vinyl ethers such as CF₃OCF═CF₂and CF₃CF₂CF₂OCF═CF₂), and fluorine-containing di-olefins such asperfluorodiallyl ether and perfluoro-1,3-butadiene. Examples of suitablenon-fluorine-containing monomers include olefin monomers such asethylene, propylene, and the like.

[0028] The VDF-containing fluoropolymer may be prepared using emulsionpolymerization techniques as described, e.g., in Sulzbach et al., U.S.Pat. No. 4,338,237 or Grootaert, U.S. Pat. No. 5,285,002, herebyincorporated by reference. Useful commercially available VDF-containingfluoroplastics include, for example, Dyneon™ THV™ 200, THV™ 400, THV™500G, THV™ 610X fluoropolymers (available from Dyneon LLC, St. Paul,Minn.), KYNAR™ 740 fluoropolymer (available from Atochem North America,Philadelphia, Pa.), HYLAR™ 700 (available from Ausimont USA, Inc.,Morristown, N.J.), and FLUOREL™ FC-2178 (available from Dyneon, LLC).

[0029] A particularly useful fluoropolymer includes interpolymerizedunits derived from at least TFE and VDF in which the amount of VDF is atleast 0.1 % by weight, but less than 20% by weight. Preferably, theamount of VDF ranges from 3-15% by weight, more preferably from 10- 15%by weight.

[0030] Examples of suitable fluoroelastomers include VDF-HFP copolymers,VDF-HFP-TFE terpolymers, TFE-propylene copolymers, and the like.

[0031] The substrate may include an inorganic substrate, such as a metalor an inorganic glass, or an organic substrate, such as a fluoropolymeror a non-fluorinated polymer. Alternatively, the substrate may be anorganic-inorganic composite. The metal may be copper or stainless steel.The inorganic glass may be a silicate. The non-fluorinated polymer maybe a polyamide, a polyolefin, a polyurethane, a polyester, a polyimide,a polyimide, a polystyrene, a polycarbonate, a polyketone, a polyurea, apolyacrylate, and a polymethylmethacrylate, or a mixture thereof. Forexample, the non-fluorinated polymer may be a non-fluorinated elastomer,such as acrylonitrile butadiene (NBR), butadiene rubber, chlorinated andchlorosulfonated polyethylene, chloroprene, ethylene-propylene monomer(EPM) rubber, ethylene-propylene-diene monomer (EPDM) rubber,epichlorohydrin (ECO) rubber, polyisobutylene, polyisoprene,polysulfide, polyurethane, silicone rubber, blends of polyvinyl chlorideand NBR, styrene butadiene (SBR) rubber, ethylene-acrylate copolymerrubber, and ethylene-vinyl acetate rubber. Suitable ethylene-vinylacetate copolymers include ELVAX™ available from E.I DuPont de NemoursCo., Wilmington, Del.

[0032] Polyamides useful as the non-fluorinated polymer are generallycommercially available. For example, polyamides such as any of thewell-known nylons are available from a number of sources. Particularlypreferred polyamides are nylon-6, nylon-6,6, nylon-11, and nylon-12. Itshould be noted that the selection of a particular polyamide materialshould be based upon the physical requirements of the particularapplication for the multi-layer article. For example, nylon-6 andnylon-6,6 offer better heat resistance properties than nylon-11 andnylon-12, whereas nylon-11 and nylon-12 offer better chemical resistanceproperties. In addition, other nylon materials such as nylon-6,12,nylon-6,9, nylon-4, nylon-4,2, nylon-4,6, nylon-7, and nylon-8 may beused, as well as ring-containing polyamides such as nylon-6,T andnylon-6, 1. Suitable nylons include VESTAMID™ L2140, a nylon-12available from Creanova, Inc. of Somerset, N.J. Polyether-containingpolyamides, such as PEBAX™ polyamides (Atochem North America,Philadelphia, Pa.), may also be used.

[0033] Useful polyurethane polymers include aliphatic, cycloaliphatic,aromatic, and polycyclic polyurethanes. These polyurethanes aretypically produced by reaction of a polyfunctional isocyanate with apolyol according to well-known reaction mechanisms. Useful diisocyanatesfor employment in the production of a polyurethane includedicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate,1,6-hexamethylene diisocyanate, cyclohexyl diisocyanate, anddiphenylmethane diisocyanate. Combinations of one or more polyfunctionalisocyanates may also be used. Useful polyols includepolypentyleneadipate glycol, polytetramethylene ether glycol,polyethylene glycol, polycaprolactone diol, poly-1,2-butylene oxideglycol, and combinations thereof. Chain extenders such as butanediol orhexandiol may also be used in the reaction. Useful commerciallyavailable urethane polymers include MORTHANE™ L424.167 (MI=9.7), PN-04or 3429 from Morton International, Seabrook, N.H. and X-4107 from B.F.Goodrich Co., Cleveland, Ohio.

[0034] Useful polyolefin polymers include homopolymers of ethylene,propylene, and the like, as well as copolymers of these monomers with,for example, acrylic monomers and other ethylenically unsaturatedmonomers such as vinyl acetate and higher alpha-olefins. Such polymersand copolymers may be prepared by conventional free radicalpolymerization or catalysis of such ethylenically unsaturated monomers.The degree of crystallinity of the polymer may vary. The polymer may,for example, be a semi-crystalline high density polyethylene or may bean elastomeric copolymer of ethylene and propylene. Carboxyl, anhydride,or imide functionalities may be incorporated into the polymer bypolymerizing or copolymerizing functional monomers such as acrylic acidor maleic anhydride, or by modifying the polymer after polymerization,e.g., by grafting, by oxidation, or by forming ionomers. Examplesinclude acid modified ethylene acrylate copolymers, anhydride modifiedethylene vinyl acetate copolymers, anhydride modified polyethylenepolymers, and anhydride modified polypropylene polymers. Such polymersand copolymers generally are commercially available, for example, asENGAGE™ (Dow-DuPont Elastomers, Wilmington, Del.) or EXACT™ (ExxonMobil,Linden, N.J.). For example, anhydride modified polyethylene polymers arecommercially available from E.I. DuPont de Nemours & Co., Wilmington,Del., under the trade designation BYNEL™ coextrudable adhesive resins.

[0035] Useful polyacrylates and polymethacrylates include polymers ofacrylic acid, methyl acrylate, ethyl acrylate, acrylamide, methacrylicacid, methyl methacrylate, ethyl methacrylate, and the like. An exampleof a polymethacrylate is EMAC™ (Chevron Chemical Co., Houston, Tex.).

[0036] Useful polycarbonate polymers include aliphatic polycarbonatessuch as polyester carbonates, polyether carbonates, and bisphenolA-derived polycarbonates, and the like.

[0037] Useful polyimide polymers include polyimide polymers made fromthe anhydride of pyromellitic acid and 4,4′-diaminodiphenyl etheravailable from E.I. DuPont de Nemours and Company under the tradenameKAPTON™. Variations include KAPTON™ H, KAPTON™ E and KAPTON™ V, amongothers.

[0038] Additional examples of useful non-fluorinated polymers, as notedabove, include polyesters, polycarbonates, polyketones, and polyureas.Commercially available examples of such polymers include SELAR™polyester (E.I. DuPont de Nemours & Co., Wilmington, Del.), LEXAN™polycarbonate (General Electric, Pittsfield, Mass.), KADEL™ polyketone(Amoco, Chicago, Ill.), and SPECTRIM™ polyurea (Dow Chemical Co.,Midland, Mich.).

[0039] Commercially available elastomers include NIPOL™ 1052 NBR (ZeonChemical, Louisville, Ky.), HYDRIN™ C2000 epichlorohydrin-ethylene oxiderubber (Zeon Chemical, Louisville, Ky.), HYPALON™ 48 chlorosulfonatedpolyethylene rubber (E.I. DuPont de Nemours & Co., Wilmington, Del.),NORDEL™ EPDM (R.T. Vanderbilt Co., Inc., Norwalk, Conn.), VAMAC™ethylene-acrylate elastomer (E.I. DuPont de Nemours & Co. Wilmington,Del.), KRYNAC™ NBR (Bayer Corp., Pittsburgh, Pa.), PERBUNAN™ NBR/PVCblend (Bayer Corp., Pittsburgh, Pa.), THERBAN™ hydrogenated NBR (BayerCorp., Pittsburgh, Pa.), ZETPOL™ hydrogenated NBR (Zeon Chemical,Louisville, Ky.), SANTOPRENE™ thermoplastic elastomer (AdvancedElastomer Systems, Akron, Ohio), and KELTAN™ EPDM (DSM ElastomersAmericas, Addis, La.).

[0040] The substrate may include a second fluoropolymer.

[0041] The substrate may have one or more surface polar functionalitypresent thereon to enhance bonding, such as, for example, an amino,carboxyl and hydroxyl functionality.

[0042] The bonding composition may be deposited on a surface of thefluoropolymer, the substrate or both. In certain embodiments, thebonding composition may be incorporated into the fluoropolymer, thesubstrate, or both, such that when the surfaces contact each other, thebonding composition contacts the fluoropolymer and the substratesimultaneously. The bonding composition may be incorporated into thefluoropolymer or the substrate by melt mixing or extruding a mixtureincluding the bonding composition. Alternatively, the bondingcomposition may be applied to a surface of the fluoropolymer orsubstrate by a process such as, for example, spray coating, curtaincoating, immersion coating, dip coating, flood coating, and the like.

[0043] The fluoropolymer and substrate may contact each other underpressure, with optional heating, to form a precursor that issubsequently exposed to actinic radiation. In certain situations, morethan one fluoropolymer layer may contact more than one surface of thesubstrate. In still other situations, two substrates may contact twosurfaces of a fluoropolymer.

[0044] Each of the fluoropolymer and the substrate, independently, maybe provided as a film or as a molded or shaped article. Preferablyeither the fluoropolymer or the substrate is substantially transmissiveto the actinic radiation.

[0045] The fluoropolymer is bonded to the substrate by exposing thebonding composition to actinic radiation. The bonding composition may beexposed to actinic radiation through the fluoropolymer, through thesubstrate, or both. In certain situations, the exposure to actinicradiation may be before the substrate contacts the fluoropolymer. Inother situations, the exposure to actinic radiation may occur after thesubstrate and fluoropolymer contact each other. In still othersituations, exposure to actinic radiation occurs simultaneously uponcontacting the substrate and the fluoropolymer.

[0046] Suitable sources of actinic radiation include arc lamps, such asxenon-arc lamps, mercury arc lamps (including low and medium pressuremercury arc lamps), fluorescent blacklights, microwave-driven lamps,such as those sold by Fusion UV Systems of Rockville, Md. (includingH-type and D-type bulbs), lasers and the like. Lamps that emit enrichedamounts of ultraviolet or blue light, such as, for example, low pressuremercury (e.g., germicidal) lamps, are preferred.

[0047] In many cases, heat, pressure, or combinations thereof, may bedesired during bonding. Suitable heat sources include, but are notlimited to, ovens, heated rollers, heated presses, infrared radiationsources, flame, and the like. Suitable pressure sources are well knownand include presses, nip rollers, and the like.

[0048] The invention will now be described further by way of thefollowing examples.

EXAMPLES

[0049] In the following examples, the term “wt %” means weight percentbased on total weight.

[0050] “THV™ 500” refers to a terpolymer of TFE/HFP/VDF, having a melttemperature of 165° C.; “THV™ 400” refers to a terpolymer ofTFE/HFP/VDF, having a melt temperature of 150° C.; “THV™ 200” refers toa terpolymer of TFE/HFP/VDF, having a melt temperature of 120° C.; “FEP”refers to FEP X6307 which is a copolymer of tetrafluorethylene andhexafluoropropylene, 85/15 by weight; “HTE” is a terpolymer ofhexafluoropropylene, teterafluoroethylene and ethylene, all availablefrom Dyneon, L.L.C. of Oakdale, Minn.

[0051] “PVDF-HV” refers to “PVDF 11010” which is a tradename for acopolymer of hexafluoropropylene and vinylidene fluoride having amelting point of 160° C.; “PVDF-CV” refers to SOLEF™ PVDF-CV which is acopolymer of chlorotrifluoroethylene and vinylidene fluoride, bothcommercially available from Soltex Polymer Corp. of Houston, Tex.

[0052] “BYNEL™ 3101” is an acid modified ethylene-vinyl acetatecopolymer; “ELVAX™ 450” is an ethylene-vinyl acetate copolymer having 18wt % vinyl acetate and a Vicat softening temperature of 61° C.;“polyimide” refers to Kapton™ 100HN film, all commercially availablefrom E.I. du Pont de Nemours of Wilmington Del.

[0053] “EMAC™ 2202T” is a copolymer of ethylene and methyl acrylate,80/20 by weight available from Chevron Chemical Co. of Houston, Tex.

[0054] “MORTHANE™ L424.167 (MI=9.7)” is an aliphatic polyurethaneavailable from Morton, International of Chicago, Ill.

[0055] “VESTAMID™ L2140” refers to nylon 12 having a Vicat softeningpoint of 140° C. commercially available from Creanova, Inc. of Somerset,N.J.

[0056] “Copper-coated polyimide” refers to Kapton™ 100HN film that hasbeen metallized with copper. “Gold-coated polyimide” refers toKapton™100HN film that has been metallized with gold.

[0057] “Polycarbonate film” refers to polyethylene terephthalate film ofabout 10 mils (0.25 mm) thickness.

[0058] Unless otherwise specified, additional materials used in theexamples were readily available from general commercial vendors suchSigma-Aldrich Chemical Co. of Milwaukee, Wis.

Example 1

[0059] Polymer films (i.e., substrates) were prepared by placing polymergranules indicated in Tables 1A and 1B were placed between two sheets ofpolytetrafluoroethylene having a thickness of 0.38 mm and softening themfor 2-3 minutes at 200° C. Subsequently, the softened materials werepressed for about 5 to 10 seconds between two heated platens of a Wabashhydraulic press (Wabash Metal Products Company, Inc., HydraulicDivision, Wabash, Ind.) and immediately transferred to a cold Wabashhydraulic press at 13-15° C. and 2-4 psi (0.014- 0.028 MPas). Aftercooling to room temperature in the cold press, round-shaped films ofpolymer having a thickness of 1.5 mm were obtained. Small pieces of thepressed films were then placed between two stainless steel plates linedwith polyethylene terephthalate-silicone coated release liners andpressed for 2-3 minutes at 200° C. with pressure and applied between twoheated platens of a Wabash hydraulic press. The films produced in thismanner were thin smooth films of 0.08 to 0.15 mm in thickness. Thesubstrate films thus prepared were cut to dimensions of approximately2.5 cm by 5 cm for use in lamination.

[0060] Two bonding compositions were prepared. Bonding composition(BC 1) was prepared by mixing 0.2 g allylamine and 0.1 gbenzyltriphenylphosphonium chloride in 2 g methanol. A second bondingcomposition (BC 2) was prepared by mixing 0.2 g allylamine and 0.1 gtriphenylphosphine in 2 g methanol. All the above chemicals wereavailable from Sigma-Aldrich Chemical Co., Milwaukee, Wis.

[0061] The cut film was flood-coated with the bonding composition. Itwas not necessary to dry the bonding composition before forming thebond. Samples were prepared by contacting a fluoropolymer film surfacewith the bonding composition-coated substrate surface to form a laminateprecursor. Comparative samples were prepared by omitting the bondingcomposition. The laminate precursor was then placed vertically in thecenter of a 254 nm photoreactor (Rayonet chamber reactor, model RPR-100equipped with sixteen low pressure mercury bulbs available from TheSouthern New England Ultraviolet, Inc. of New Haven, Conn. These sampleswere irradiated for periods of time indicated in Tables 1A and 1B.

[0062] After irradiation samples were subjected to hot lamination ontothicker films (1-1.5 mm) of their respective materials for 2 minutes at200° C. in order to obtain accurate adhesion measurement because theirradiated samples were too thin and film stretching/rupturing would beexpected during the measurement.

[0063] Peel strength was used to determine the degree of bonding. Peelstrength was determined in accordance with AS™ D-1876 (T-peel test). AnInstron™ model 1125 tester, available from Instron Corp., Canton, Mass.set at a 4 inch (10.2 cm) per minute crosshead speed was used as thetest device. The peel strength was calculated as the average loadmeasured during the peel test. The measured peel strength is shown inTables 1A and 1B. Comparative experiments showed that no adhesionbetween substrates and fluoropolymer films was observed prior toirradiation with the bonding composition present.

Example 2

[0064] Glass microscope slides and stainless steel panels (1 inch (2.54cm) by 2 inch (5.08 cm) pieces were cleaned with acetone. A surface ofthe glass or steel substrate was coated with a bonding composition, anda piece of fluoropolymer film was subsequently laminated onto the coatedsubstrate in a good surface contact. A strip of silicone liner wasinserted along the short edge between the substrate surface and thefluoropolymer film to provide tabs for the peel test. The laminatedsample was positioned vertically in the center of a 254 nm photoreactoras described in Example 1 and irradiated for a period of time as shownin Tables 1A and 1B. The measured peel strength is shown in Tables 1Aand 1B.

Example 3

[0065] Instead of fluoropolymer film, a solution of 25% fluoroelastomerFLUOREL™ FC-2145, a raw gum dipolymer of VDF and HFP, (available fromDyneon, LLC) in methanol was coated onto the side of a glass slidehaving the bonding composition. The fluoroelastomer-coated glass wasthen subjected to irradiation at 254 nm in a photoreactor as describedin Example 1 for a period of time as shown in Tables 1A and 1B. Adhesionbetween the fluoroelastomer and glass was found. TABLE 1A BC 1 BC 2 BC 3Comparative Irrad. Irrad. Irrad. Adhesion time Adhesion time AdhesionTime Adhesion Laminate (N/cm) (min) (N/cm) (min) (N/cm) (min) (N/cm)ELVAX ™ 0 10 18.9 10 25.3 20 4.9 450/THV ™400 ELVAX ™ 0 5 19.0450/THV ™400 ELVAX ™ 0 45 15 450/THV ™200 ELVAX ™ 0 45 14.4 450/THV ™500BYNEL ™ 0 10 14 10 13 3101/THV ™400 BYNEL ™ 0 5 14.4 3101/THV ™500BYNEL ™ 0 45 17 3101/THV ™200 EMAC ™ 0 10 17 10 25.2 2220/THV ™400 156.7 EMAC ™ 0 5 19.8 2220/THV ™400 EMAC ™ 0 45 5.8 2220/THV ™200 EMAC ™ 045 5.8 2220/THV ™500 VESTAMID ™ 0 15 24.3 15 19.0 L2140/THV ™400MORTHANE ™ 0 15 8.8 15 20.4 L424.167, MI = 9.7/THV ™ 400 ENGAGE ™ 0 205.1 20 0 8402/THV ™400 ENGAGE ™ 0 20 33.1 8402/PVDF EXACT ™ 0 20 104015/PVDF EXACT ™ 0 20 4.4 4015/THV ™400 Polyester/THV400 0 30 3.2

[0066] TABLE 1B BC 1 BC 2 Comparative Irrad. Irrad. Adhesion timeAdhesion time Adhesion Laminate (N/cm) (min) (N/cm) (min) (N/cm) ELVAX ™0.4 15 24.7 15 18.6 4501/PVDF ELVAX ™ 0.4 10 19.2 4501/PVDF ELVAX ™ 0.45 2.8 4501/PVDF BYNEL ™ 1 15 19.7 15 36.0 3101/PVDF BYNEL ™ 1 15 6.7 1026.6 3101/PVDF BYNEL ™ 1 5 11 3101/PVDF EMAC ™ 0 15 23.2 15 26.62220/PVDF EMAC ™ 0 10 17.8 2220/PVDF EMAC ™ 0 5 9.0 2220/PVDF ELVAX ™ 020 174 450/SOLEF ™ HV BYNEL ™ 0 20 28.0 3101/SOLEF ™ HV EMAC ™ 0 20 25.42220/SOLEF ™ HV BYNEL ™ 0 20 21.2 3101/SOLEF ™ CV EMAC ™ 0 20 26.12220/SOLEF ™ CV Glass/THV ™400 0 45 Good 45 Good Steel/THV ™400 0 45Good 45 Good Glass/Fluorel ™ 0 45 Good FC-2145

Example 4

[0067] The procedure of Example 1 was followed using the bondingcomposition (BC) and comparative compositions (COMP) listed in Tables 2Aand 2B, except that cut fluoropolymer film was coated with the bondingcomposition or comparative compositions. Subsequently, a secondfluoropolymer film was placed on the bonding composition to form alaminate precursor. The precursor was then placed vertically in thecenter of a 254 nm photoreactor (Rayonet chamber reactor, model RPR-100equipped with sixteen low pressure mercury bulbs. Samples wereirradiated for periods of time indicated in Tables 3A-4. Afterirradiation, the two pieces of fluoropolymer films were peeled apart andindividually laminated to bonding substrates to form the finalmultiplayer articles. A strip of a silicon liner was inserted about 0.6cm into the space between the layers along the short edge for peeltesting. The article was hot pressed at 200° C. for 2 minutes andimmediately transferred to a cold Wabash hydraulic press 13-15° C. Aftercooling to room temperature in the cold press, the sample was ready forpeel testing. TABLE 2A Composition Ingredients BC4 Diphenyliodoniumchloride (0.02 g) + allylamine (0.2 g) + acetonitrile (2. g) COMP4Diphenyliodonium chloride saturated in (comparative) acetonitrile (2.0g) BC5 Tetraphenylarsonium chloride (0.03 g) + allylamine (0.2 g) +acetonitrile (2.0 g) COMP5 Tetraphenylarsonium chloride (0.03 g) +acetonitrile (comparative) (2.0 g) BC6 Tetraphenylarsonium chloride(0.05 g) + ethylenediamine (0.2 g) + acetonitrile (2.0 g) COMP6Tetraphenylarsonium chloride (0.05 g) + (comparative) acetonitrile (2.0g) BC7 Triphenylsulfonium chloride (0.05 g) + allylamine (0.2 g) +acetonitrile (2.0 g) COMP7 Triphenylsulfonium chloride (0.05 g) +(comparative) acetonitrile (2.0 g) BC8 Triphenylsulfonium chloride (0.05g) + n-butylamine (0.2 g) + acetonitrile (2.0 g) BC9 Triphenylsulfoniumchloride (0.05 g) + diallylamine (0.2 g) + acetonitrile (2.0 g) BC10Phenyltrimethylammonium chloride(saturated) + allylamine (0.2 g) +acetonitrile (2.0 g) COMP10 Phenyltrimethylammoniumchloride(saturated) + (comparative) acetonitrile (2.0 g) BC11Tetraphenylphosphonium chloride (0.1 g) + allylamine (0.2 g) +acetonitrile (2.0 g) COMP11 Tetraphenylphosphonium chloride (0.1 g) +acetonitrile (comparative) (2.0 g) BC12 Tetrabutylphosphonium chloride(0.1 g) + allylamine (0.2 g) + acetonitrile (2.0 g) COMP12Tetrabutylphosphonium chloride (0.1 g) + acetonitrile (comparative) (2.0g) BC13 Diphenyl sulfide (0.1 g) + allylamine (0.2 g) in + acetonitrile(2.0 g) COMP13 Diphenyl sulfide (0.1 g) + acetonitrile (2.0 g)(comparative)

[0068] TABLE 2B Composition Ingredients BC14 Diphenyl sulfone (0.1 g) +allylamine (0.2 g) + acetonitrile (2.0 g) COMP14 Diphenyl sulfone (0.1g) + acetonitrile (2.0 g) (comparative) BC15 Anisole (0.1 g) +allylamine (0.2 g) + acetonitrile (2.0 g) COMP 15 Anisole (0.1 g) +acetonitrile (2.0 g) (comparative) BC16 Biphenyl (0.1 g) + allylamine(0.2 g) + acetonitrile (2.0) COMP16 Biphenyl (0.1 g) + acetonitrile (2.0g) (comparative) BC17 4,4'-dihydroxybiphenyl (0.1 g) + allylamine (0.2g) + acetonitrile (2.0 g) COMP17 4,4'-dihydroxybiphenyl (0.1 g) +acetonitrile (2.0 g) (comparative) BC18 Diphenyl ether (0.1 g) +allylamine (0.2 g) + acetonitrile (2.0 g) COMP18 Diphenyl ether (0.1g) + acetonitrile (2.0 g) (comparative) BC19 Anisole (0.1 g) + aniline(0.2 g) + acetonitrile (2.0 g) COMP19 Anisole (0.1 g) + acetonitrile(2.0 g) (comparative) BC20 Chlorobenzene (0.1 g) + allylamine (0.2 g) +acetonitrile (2.0 g) COMP20 Chlorobenzene (0.1 g) + acetonitrile (2.0 g)(comparative) BC21 Biphenyl (0.1 g) + n-butylamine (0.2 g) +acetonitrile (2.0 g) COMP21 Biphenyl (0.1 g) + acetonitrile (2.0 g)(comparative) BC22 Pyrene (0.1 g) + n-butylamine (0.2 g) + acetonitrile(2.0 g) COMP22 Pyrene (0.1 g) + acetonitrile (2.0 g) (comparative) BC23Anisole (0.1 g) + 3-aminopropyltriethoxysilane (0.2 g) + acetonitrile(2.0 g) COMP23 Anisole (0.1 g) + acetonitrile (2.0 g) (comparative) BC24Diphenyl sulfide (0.1 g) + 3-aminopropyltriethoxysilane (0.2 g) +acetonitrile (2.0 g) COMP24 Diphenyl sulfide (0.1 g) + acetonitrile (2.0g) (comparative) BC25 Anisole (0.1 g) + 3-aminopropyltriethoxysilane(0.2 g) + acetonitrile (2.0 g) COMP25 Anisole (0.1 g) + acetonitrile(2.0 g) (comparative) BC26 Anisole (0.1 g) + ethylenediamine (0.2 g) +acetonitrile (2.0 g) BC27 Anisole (0.1 g) + aminoethanol (0.2 g) +acetonitrile (2.0 g) COMP27 Anisole (0.1 g) + acetonitrile (2.0 g)(comparative) BC28 Tetraphenylarsonium chloride (0.05 g) + allylamine(0.2 g) + acetonitrile (2.0 g)

[0069] TABLE 3A Irradiation time Peel Strength Sample BC at 254 nm (min)(N/cm) FEP/VESTAMID ™ BC4 10 15.84 L2140 FEP/VESTAMID ™ COMP4 10 0 L2140FEP/VESTAMID ™ BC5 10 14.08 L2140 FEP/BYNEL ™ 3101 BC5 10 21.12FEP/VESTAMID ™ COMP5 10 0 L2140 FEP/BYNEL ™ 3101 COMP5 10 0FEP/VESTAMID ™ BC6 5 14.08 L2140 FEP/BYNEL ™ 3101 BC6 5 8.8FEP/VESTAMID ™ COMP6 5 0 L2140 FEP/BYNEL ™ 3101 COMP6 5 0 FEP/VESTAMID ™BC7 5 cohesive FEP L2140 failure FEP/BYNEL ™ 3101 BC7 5 5.28FEP/VESTAMID ™ COMP7 5 0 L2140 FEP/BYNEL ™ 3101 COMP7 5 0 FEP/VESTAMID ™BC8 10 8.8 L2140 FEP/BYNEL ™ 3101 BC8 10 11.44 FEP/VESTAMID ™ BC9 10cohesive FEP L2140 failure FEP/BYNEL ™ 3101 BC9 10 cohesive FEP failureFEP/VESTAMID ™ BC10 15 cohesive FEP L2140 failure FEP/BYNEL ™ 3101 BC1015 10.56 FEP/VESTAMID ™ COMP10 15 0 L2140 FEP/BYNEL ™ 3101 COMP10 15 0FEP/VESTAMID ™ BC11 5 cohesive FEP L2140 failure FEP/BYNEL ™ 3101 BC11 514.08 FEP/VESTAMID ™ COMP11 5 0 L2140 FEP/BYNEL ™ 3101 COMP11 5 0FEP/VESTAMID ™ BC12 10 cohesive FEP L2140 failure FEP/BYNEL ™ 3101 BC1210 8.8 FEP/VESTAMID ™ COMP12 10 0 L2140 FEP/BYNEL ™ 3101 COMP12 10 0

[0070] TABLE 3B Irradiation time Peel Strength Sample BC at 254 nm (min)(N/cm) FEP/VESTAMID ™ L2140 BC13 5 >22.8 FEP/BYNEL ™ 3101 BC13 5 15.8FEP/VESTAMID ™ L2140 COMP13 5 0 FEP/BYNEL ™ 3101 COMP13 5 0FEP/VESTAMID ™ L2140 BC14 5 >12.3 FEP/BYNEL ™ 3101 BC14 5 12.3FEP/VESTAMID ™ L2140 COMP14 5 0 FEP/BYNEL ™ 3101 COMP14 5 0FEP/VESTAMID ™ L2140 BC15 5 6.1 FEP/BYNEL ™ 3101 BC15 5 7.0FEP/VESTAMID ™ L2140 COMP15 5 0 FEP/BYNEL ™ 3101 COMP15 5 0FEP/VESTAMID ™ L2140 BC16 5 >22.8 FEP/BYNEL ™ 3101 BC16 5 12.3FEP/VESTAMID ™ L2140 COMP16 5 0 FEP/BYNEL ™ 3101 COMP16 5 0FEP/VESTAMID ™ L2140 BC17 5 >19.3 FEP/BYNEL ™ 3101 BC17 5 7.9FEP/VESTAMID ™ L2140 COMP17 5 1.8 FEP/BYNEL ™ 3101 COMP17 5 0FEP/VESTAMID ™ L2140 BC18 5 7.9 FEP/BYNEL ™ 3101 BC18 5 9.7FEP/VESTAMID ™ L2140 COMP18 5 0 FEP/BYNEL ™ 3101 COMP18 5 0FEP/VESTAMID ™ L2140 BC19 5 24.6 FEP/BYNEL ™ 3101 BC19 5 8.8FEP/VESTAMID ™ L2140 COMP19 5 0 FEP/BYNEL ™ 3101 COMP19 5 0FEP/VESTAMID ™ L2140 BC20 5 >22.8 FEP/BYNEL ™ 3101 BC20 5 12.3FEP/VESTAMID ™ L2140 COMP20 5 0 FEP/BYNEL ™ 3101 COMP20 5 0

[0071] TABLE 3C Irradiation time Peel Strength Sample BC at 254 nm (min)(N/cm) FEP/VESTAMID ™ BC21 5 8.8 L2140 FEP/BYNEL ™ 3101 BC21 5 30.7FEP/VESTAMID ™ COMP21 5 0 L2140 FEP/BYNEL ™ 3101 COMP21 5 0FEP/VESTAMID ™ BC22 5 >22.8 L2140 FEP/BYNEL ™ 3101 BC22 5 12.3FEP/VESTAMID ™ COMP22 5 0 L2140 FEP/BYNEL ™ 3101 COMP22 5 0FEP/VESTAMID ™ BC23 10 26.3 L2140 FEP/BYNEL ™ 3101 BC23 10 30.7FEP/VESTAMID ™ COMP23 5 0 L2140 FEP/BYNEL ™ 3101 COMP23 5 0FEP/VESTAMID ™ BC24 5 17.5 L2140 FEP/BYNEL ™ 3101 BC24 5 29.8FEP/VESTAMID ™ COMP24 5 0 L2140 FEP/BYNEL ™ 3101 COMP24 5 0FEP/VESTAMID ™ BC25 5 14.9 L2140 FEP/BYNEL ™ 3101 BC25 5 13.2FEP/VESTAMID ™ COMP25 5 0 L2140 FEP/BYNEL ™ 3101 COMP25 5 0FEP/VESTAMID ™ BC26 5 7.0 L2140 FEP/BYNEL ™ 3101 BC26 5 33.3FEP/VESTAMID ™ COMP26 5 0 L2140 FEP/BYNEL ™ 3101 COMP26 5 0 FEP/EXACT ™4015 BC27 10 6.1 FEP/VESTAMID ™ BC28 5 >15.8 L2140

Example 5

[0072] This comparative example shows that electron donors are noteffective at promoting bonding according to the invention. Table 4 showsthe bonding results obtained when electron donors were used as a 10weight percent solution in methanol according to the procedure ofExample 1. TABLE 4 Electron Donor as Irradiation a 10 wt % in Time at254 Sample Methanol nm (min) Peel (N/cm) FEP/VESTAMID ™ Allylamine 5 0L2140 FEP/Bynel3101 Allylamine 5 0 FEP/VESTAMID ™ n-butylamine 5 0 L2140FEP/Bynel3101 n-butylamine 5 0 FEP/VESTAMID ™ 3-aminopropyl- 5 0 L2140triethoxysilane FEP/Bynel3101 3-aminopropyl- 5 <1.75 triethoxysilaneFEP/VESTAMID ™ 2-aminoethanol 5 <1.75 L2140 FEP/Bynel3101 2-aminoethanol5 <1.75 FEP/VESTAMID ™ 1,2-ethylenediamine 5 <1.75 L2140 FEP/Bynel31011,2-ethylenediamine 5 <1.75

What is claimed is:
 1. A method of bonding a fluoropolymer to asubstrate comprising: forming a mixture including a fluoropolymer and abonding composition, the bonding composition including an amine and alight-absorbing compound selected from the group consisting of anammonium compound, a phosphonium compound, a sulfonium compound, asulfoxonium compound, an iodonium compound, an arsonium compound, andcombinations thereof; and contacting a surface of the mixture with asurface of a second component; and exposing the bonding composition toactinic radiation.
 2. The method of claim 1, wherein the light-absorbingcompound includes an ammonium compound.
 3. The method of claim 1,wherein the light-absorbing compound includes a phosphonium compound. 4.The method of claim 1, wherein the amine is selected from the groupconsisting of a primary amine, an amino-substituted organosilane, andcombinations thereof.
 5. The method of claim 4, wherein the amine is analkylamine.
 6. The method of claim 5, wherein the alkylamine is afluoroalkylamine.
 7. The method of claim 1, wherein the amine is anamino-substituted organosilane having a hydrolyzable substituent.
 8. Themethod of claim 1, wherein the bonding composition includes a vinylsilane.
 9. The method of claim 1, wherein the fluoropolymer is aperfluorinated polymer.
 10. The method of claim 1, wherein thefluoropolymer is a partially fluorinated polymer.
 11. The method ofclaim 1, wherein the bonding composition is exposed to actinic radiationthrough the fluoropolymer.
 12. The method of claim 1, wherein theactinic radiation has a wavelength maximum of between 190 nm and 400 nm.13. The method of claim 1, wherein the actinic radiation has awavelength maximum of between 210 nm and 290 nm.